Androgens estrogens produced from

Changes in androgen production also occur during the menstrual cycle, with a peak at midcycle. Estradiol is not the only estrogen produced estrone secretion, mainly from... 

Local production of estrogens by the aromatization of androgens may play a causal role in the development or progression of diseases such as breast cancer. Estrogens also may be produced from androgens by CYPI9 in the central nervous system (CNS) and other tissues and exert local effects near their production site fe.g., in bone they increase bone mineral density). 

Testosterone is an androgenic hormone (male sex hormone) produced in the testes, and estradiol is an estrogenic hormone (female sex hormone) produced from testosterone in the ovaries. Both compounds play a number of biological roles, ranging from the development of secondary sex characteristics to the promotion of tissue and muscle growth. 

The estrogens are a family of hormones synthesized in a variety of tissues. 17P-Estradiol is the primary estrogen of ovarian origin. In some species, estrone, synthesized in numerous tissues, is more abundant. In pregnancy, relatively more estriol is produced, and this comes from the placenta. The general pathway and the subcellular localization of the enzymes involved in the early steps of estradiol synthesis are the same as those involved in androgen biosynthesis. Features unique to the ovary are illustrated in Figure 42-7. 

It seems probable from our discussion that individual normal males, for example, vary through wide limits (possibly 10-fold or more) in their production of both androgens and estrogens. If we classify individual men roughly as (1) low, (2) intermediate, and (3) high producers of each of the two types of hormones, we find that an... 

Fig. 4. The gonadotrophin two-cell model of ovarian steroidogenesis involves the stimulation of thecal cells by LH to produce androstenedione and testosterone while FSH stimulates granulosa cells to synthesize estrogens from the theca-derived androgens.

Female Hormones. Closely related 10 the male androgenic hormones, and probably synthesized from them in the female organism, are the estrogenic hormones which are produced principally in the ovary. Although / -estradiol is die normally secreted ovarian hormone, a number or ulher estrogenic substances have been isolated from urine and from animal studies. They include o-cstradiol. esiriol, and estrone. The structures of these hormones are given in Fig. 2. 

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